(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Biodiversity Heritage Library | Children's Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "London water supply"

LONDON WATER SUPPLY. 



L 



The improvement of the Water Supply of London and its suburbs 
is recognised to be one of the most important questions of the day. 
The appointment of a Royal Commission to inquire into the best mode 
of dealing with this grave want ; and the experience of individuals in 
every district in and about London indicates the need of a prompt, and, 
if possible, a complete solution of the means of providing an unfailing 
supply of pure soft water, which supply should be large enough not 
only to meet the wants of the present population, but should suffice for 
the contingent and probable increase of population in a lon^ futurity. 

It is proposed by the author to strengthen the conclusion of the 
Legislature and of the public as to the absolute and prompt necessity 
for this work, by reference to the experience of the past year, excep- 
tional in the short rainfall in the months of April, Hay, June, July, 
and the early part of August. It is further proposed to show the 
pecuniary loss arising to the community from the impure character of 
the water supplied, apart from its important influence on the health 
of the population, on which no reliable data exist. Finally, to point 
out a source from which water may be supplied in almost unlimited 
quantities of excellent quality, both for sanatory and commercial 
purposes, and at a cost moderate, in comparison to the benefit its use 
will confer. 

During the last summer (1868) measurements were taken of the 
quantity of water passing down the Eiver Thames at Sunbury, which 
is above the points where the London "Water Companies abstract their 
supply. It was then found that the yield was about 256,000,000 
gallons per diem. Deducting from this amount 58,000,000 gallons — 
the quantity daily abstracted by the five London Water Companies — 
there would remain 198,000,000 gallons only to pass down the river 



daily, so that the scouring power of the backwater would be seriously 
reduced, and the silting-up of the low water channels below would be 
thereby much aggravated. 

In fact, owing to this abstraction and the diminished volume of 
water consequent on the dry season of the past year, there has 
occurred, in the low water channel of the river — particularly between 
London Bridge and the sea — a diminution of depth arising from the 
accumulation of silt, sewage, and other matters, which have been 
principally deposited by the flood tides, and which the deficient supply 
of upland water and the ebb-tide have failed to clear away. This 
important matter appears to have been almost overlooked by the 
authority which is usually considered as the proper guardian of navi- 
gation interests — namely, the Conservancy Board. It can hardly be 
credited, by those unacquainted with the fact, that the Conservancy 
Board receives the greater portion of its income in the shape of an 
annual payment from the five London Water Companies, for allowing 
them to make the enormous abstraction of water which is required for 
the daily Water Supply of London. In addition to the five companies 
above alluded to, the East London Water Company, which at present 
takes its supply solely from the Eiver Lea, has obtained an Act which 
gives that Company the power to abstract a further 10,000,000 gallons 
a day from the Thames near Sunbury ; and to effect that purpose the 
works of that Company are now in course of execution. 

The injurious effects upon the condition of the Thames is but one of 
the many objections which may be urged against the present mode of 
supply. Scientific opinions and official reports lead to the almost 
general conviction that the present resources of the London Water 
Companies are altogether inadequate in quantity, and the water sup- 
plied by them so far defective in quality, as to lead to the production 
of many sanatory evils. The point indeed remaining for consideration 
is to determine the best means of enlarging the supply of pure water to 
an extent commensurate with the ever-increasing demands of the vast 
population occupying the metropolitan area. 

The suggestion that such a supply should be derived from the 
affluents of the Thames, by storing the flood waters in impounding 
reservoirs constructed for the purpose, at first sight commends itself, 
but in any plan yet proposed, practical objections have existed, which 



i^f»4 



^utuc 



have hitherto been considered insurmountable. It must also be re- 
membered that any supply drawn from the Thames Basin must 
inevitably be of the present hard character owing to the geological 
nature of the district^ the strata being chiefly of the Chalk, Oolitic and 
Lias formations. The force of this objection of hardness of water to the 
Thames basin as a source of supply, will be more fully shown in a 
subsequent paragraph. 

Dismissing the Thames basin as undesirable, the nearest source to 
which we can look for the "Water Supply of London is Wales. The 
two principal Elvers of Wales are the Severn and the Wye, which rise 
within a few miles of each other. Both of these rivers are, naturally, 
capable of affording an abundant supply of pure water. 

The plan proposed by the author is to collect in the watersheds of 
the upper sources of the Eiver Wye, on the southern slopes of the 
Plynlymnon range, an ample supply of pure, soft, and wholesome 
water, and to conduct it, by means of gravitation only, to London. 

The Wye basin being more thinly inhabited than the other large 
river basins of England and Wales, its water is at present of less 
utility, and its proposed abstraction will be of less inconvenience than 
in any other case. The Thames basin above Hampton contains on the 
average a population of 224 to the square mile, and the Severn above 
Tewkesbury 378, whilst the Wye above Monmouth contains 97 only 
to the square mile. 

The only application of the water of the Wye to mechanical pur- 
poses is for flour mills, of which there are very few, and these will not 
be injuriously affected by the proposed plan. The fisheries which 
exist on the Eiver Wye will also be protected from injury. 

Owing to the rapidity of the current of the Wye and to the 
absence of any important towns on the river, with the exception of 
Hereford, there is but little navigation. That which does exist is 
chiefly confined to the tidal portion of the river between Chepstow 
and the Severn Estuary, and consequently the injury that would arise 
in this respect from the abstraction of water from the Wye would be 
very insignificant. 

It is this consideration which obviously renders the Eiver Wye 
preferable as a source of supply to the Severn. On the latter river 
are many large and important towns involving considerable internal 



communication by river navigation ; furtlier, the current is less rapid, 
and the abstraction of a large volume of water would be more ap- 
preciable in the Severn than in the "Wye. 

At the Twelfth Annual Meeting of the Canal Association held at 
Birmingham in January 1869, Mr. E. Leader Williams, speaking of the 
Eiver Severn, and particularly in connection with Mr. Bateman's project 
for the abstraction of that which is designated as the surplus water of the 
Severn to the extent of 200,000,000 gallons per day, observed ''that 
nothing was known of any surplus ivater, inasmuch as the maintenance 
of the estuary of the river is dependant upon the velocity and volume 
of the winter floods, without which the estuary and the whole of the 
lower reaches of the river would become choked with mud and silt 
brought up by the far too powerful spring tides. The tendency of 
these tides to choke up the lower reaches of the Severn had been 
specially demonstrated during the drought of the past summer as 
the deep reaches and pools near Gloucester became so filled with 
deposit as to prevent navigation excepting upon the top of Spring 
Tides." 

The upper portions of the Severn and "Wye are of the same 
geological character, both being on the Silurian formation. The 
physical features of these districts are also very similar, and it may 
therefore safely be assumed that the water of one will be almost 
precisely of the same chemical nature as that of the other. Dr. 
Bobert Dundas Thomson, F.E.S., found in his analyses of the water 
in the upper tributaries of the Severn, that where there was no con- 
tamination from manufactories or sewage, the hardness was less than 
two degrees, and that in 100,000 parts of water the total impurity 
was about four parts. 

According to the analyses made by the eminent chemist Dr. 
Frankland, for the Begistrar-General, the average hardness of the 
water supplied to London by the existing Water Companies is about 
twenty degrees, and in 100,000 parts there are about twenty parts of 
solid impurities. 

The water which, by the proposed plan, it is intended to bring to 
London is undoubtedly of an extremely soft and pure character, and 
its introduction would not only be very desirable as regards the health 
of the inhabitants, but would effect a great saving both for domestic 



and manufacturing purposes, especially in such articles as soap and 
soda. In Glasgow, where the water is obtained from Loch Katrine, 
and is very similar in character to that of the upper tributaries of the 
"Wye, there are several manufactories carried on, which cannot profitably 
compete in other places on account of the water not being of so soft a 
quality as that of Glasgow. It is stated, on the high authority of Mr. 
Bateman, the eminent engineer who constructed the Glasgow "Water- 
works, that in that city there has been an annual saving in soap and 
soda alone, of £36,000 on a population of 400,000 persons, by the 
substitution of Loch Katrine water which is of one degree of hardness, 
instead of water from the Clyde of from seven degrees to nine degrees 
of hardness. As the water supplied by the London "Water Companies 
is on the average of more than twenty degrees of hardness, whilst the 
water proposed to be introduced is nearly equal in softness to that 
of Loch Katrine, and as the population of London now exceeds 
3,000,000, the probable annual saving in soap and soda, if taken 
in proportion to llr. Bateman's estimate for Glasgow, would exceed 
£500,000 per annum. To show the value of soft water, it may 
be mentioned that at Hammersmith and the vicinity many house- 
holders pay from Is. 6d. to 2s. a butt for artesian well water, which 
is of a softer character, in preference to the Company's water, 
which is supplied at a cost of about one-twentieth of the price 
of the well water. The water supplied by the London "Water Com- 
panies when used for steam boiler purposes clearly indicates its hard 
quality by the solid incrustation that takes place in the boilers ; this 
is very difficult to remove, and is consequently very injurious, and 
increases the chances of accident. 

The rainfall of the proposed district, which is very elevated, is known 
to be very great, and as the configuration and position of this part of 
"Wales, with reference to the Atlantic Ocean, is very similar to the 
Lake district, it may safely be assumed that the rate of yield of these 
districts will be nearly equal. 

In the Lake district the minimum annual rainfall, which is the 
proper datum to found conclusions upon, is 60 inches. If, however, 
we take for the "Wye sources only 42 inches, in order that there may 
be no chance of exaggeration in the calculations, we shall have, after 
deducting 12 inches for evaporation and absorption, which is a fair 



I 



6 

quantity to allow in a district such as the one in question, an available 
annual rainfall of 30 inches, or 6 inches less than is taken by the 
engineer for the kindred district of the Severn watershed. 

The proposed gathering grounds may be divided into four districts, 
the areas of which are as follows — 

Ho. 1. 93,752 acres, jor 146 square miles. 
„ 2. 80,181 „ „ 125 
„ 3. 64,903 „ „ 102 
„ 4. 42,915 „ „ 67 



Total Area .. 281,761 acres or 440 square miles. 

The total quantity of water which it is estimated the gathering 
grounds are capable of supplying, after allowing one-fourth of the avail- 
able rainfall for compensation is 393,000,000 gallons a day. However, 
as the time when this large quantity of water will be required for 
London is very remote, it is proposed, in the first instance, to collect 
the waters in the first district only, which will yield a daily quantity 
to London of 130,000,000 gallons, and to bring the other districts 
successively into use, as required by the wants of the increasing 
population. 

In order to economize the water to the fullest extent, it is intended 
to construct impounding reservoirs in the respective watersheds, of 
sufficient capacity to hold 150 days' supply, including that for compen- 
sation, so that, during the longest possible drought, there will be no 
diminution in the quantity delivered to London. Six impounding 
reservoirs, of a total capacity of 26,250 million gallons are proposed to 
be made in District "Eo. 1, and in the other districts there are suitable 
sites, where reservoirs can be made when required, of proportionate 
size, to store the water in the respective watersheds. 

It is intended to bring the water, after allowing the matter in 
mechanical suspension during floods to settle, from the impounding 
reservoirs to London by means of a conduit which will have sufficient 
fall to carry the water by gravitation. 

The conduit will commence at the most southerly of the impounding 
reservoirs in District Ko. 1, which reservoir will be placed in the Elan 
Yalley, at a point about a mile and a half below Ehayader. 

At the commencement it will be at a height of about 590 feet above 



Ordnance Datum ; it will continue along the valley of the "Wye, 
past Glasbury, Stourport, Bromsgrove, Henley-in-Arden, "Warwick, 
Banbury, Tring, and Watford, to a point near Barnet, where it will 
be brought into the service reservoirs at a height of 276 feet above 
Ordnance Datum. 

Wherever valleys of a considerable depth have to be crossed, the 
water will be conveyed by means of inverted syphons, and in these 
cases, pipes will at first be laid down, of suflScient capacity to convey 
only 130,000,000 gallons a day, as the additional pipes necessary 
for a further supply, can be laid down when more water is required 
to supply the wants of London. In all other cases the conduit will be 
of sufficient capacity to convey 230,000,000 gallons a day. Where 
hills have to be penetrated, the conduit will be in tunnel, and for a 
considerable portion of the remainder of its course it will be covered 
where it is necessary to protect the water from contamination. 

It is estimated that the total length of the conduit will be 180 miles. 

The service reservoirs for which a very convenient site has been 
chosen at Totteridge, near Barnet, will be at a distance of eight miles 
from the Marble Arch. They will be capable of containing twenty 
days supply of 130,000,000 gallons a day. 

It is intended to lay down pipes from the service reservoirs to the 
mains of all the existing Water Companies, by which means and 
without the aid of pumping a constant supply can be afforded. 

Wherever the existing pipes are not sufficiently strong to bear the 
pressure that will be brought on them, they will either be replaced, 
or in certain low lying districts the pressure will be reduced by 
partially shutting off the water. 

Water might be supplied to Birmingham and other towns which lie 
near the course of conduit, and as it would be only right that these 
towns, if so supplied, should contribute towards the expenses of the 
undertaking, the cost to the inhabitants of London would be propor- 
tionately reduced. 

The cost of the first portion of the scheme to bring 130 million 
gallons a day to London, the conduit (with the exception of the 
inverted syphons) being made large enough to bring 230 million gallons 
daily is estimated to be £7,000,000. 

The additional cost for completing all the works necessary to supply 



8 

230 million gallons a day would be £2,000,000, making altogether a 
total outlay of £9,000,000. 

The present is considered an opportune time for carrying out an 
extensive engineering operation, such as the one above referred to, 
owing to the serious dearth of employment existing throughout tho 
country among the class of workmen usually employed on similar 
undertakings, and also to the now low price of iron and other materials. 
On this ground, it is submitted the project earnestly recommends itself 
to the attention of the Government, not with the view of asking the 
smallest contribution from the public Exchequer, but through Govern- 
ment aid, to secure the facilities necessary for obtaining legislative 
sanction to such a measure at a moderate outlay. 

HAMILTON H. FULTOX. 



22, Geeat Geoege Steeet, 

WESTiTIXSTEE. 



April, 1869. 



% 



•^ 



m